Method of and apparatus for forming articles of pulp



Oct. 18, 1932. B. c. ROOT 1,882,937

METHOD oF AND APPARATUS FOR FORMING ARTICLES 0F Pugg Filed Feb. 5, 1951 f 2 sheets-Sheet 1 WKN ,0,

l.. @o @OV Il JW, l Lil W Oct. 18, 1932. B. c. ROOT 1,882,937

METHOD OF AND APPARATUS FOR FORMING ARTICLES OF PULP Filed Feb. 5, 1931 2 Sheets-Sheet 2 Patented Oct. -1 8, 1932 UNITED STATES PATENT OFFICE BERTWELL C. ROOT, OF BERLIN, NEW HAMPSHIRE, ASSIGNOR-TO BROWN COMPANY, OF BERLIN, NEW HAMPSHIRE, A CORPORATION 0I*1 MAINE METHOD OF AND APPARATUS FOR FORMIN'G ARTICLES 0F PULP Application led February 5, 1931. Serial No. 513,600.

This invention relates to the art of molding various articles of cellulosic pulp. There are many materials for which cellulosic pulp is a suitable material provided the V fibers can be suiliciently interfelted in the article to lend it reasonable mechanical strength. For example, with the increasing use of waterproofed liber conduit for Atelephone wires, power cables and the like, a i

growing need hasA arisen for such articles as bell-mouth ends for conduits where they open into manholes, also temporary plugs for conduit ends. Fiber articles are moreover entering many other fields of usefulness,

including, for example, high tension insulators or parts thereof. According to the invention suitable screen molds are provided, together with apparatus for surrounding the molds with an aqueous suspension of pulp,

and at the same time producing a considerable vacuum within the molds. AUnbeaten long-fiber pulp is preferably employed to accelerate the building up of suitable wall thickness about the mold and to provide an article which is adapted to be readily saturated with suitable waterproofing materials such as molten pitch.

For a more complete understanding of the invention referencefmay .be had to the dcscription thereof which follows hereinafter,

and to the drawings, of which,-#

Figure 1 is a plan view of apparatus embodying the invention. y

Figure 2 is an elevation of the same, a portion being broken away..

Figure 8 is anend elevation, a vportion being shown in section. v

Figure 4 is a perspective view of a typical molded article.

Figure 5 is a section on the line'5-5 of Figure 4.

The apparatus shown in the drawings includes a number of suitable molds 10 which may bemounted side byside in an elongated flow box 11. Each mold 10 may be made with a surface of Fourdrinier wire backed by a. frame of sulicient strength to hold the wire in shape when there is a high vacuum within the mold. Within ths box there may be a pair 60 of parallel partitions 12 and 13 extending from one end of the box to the other and dividing the box into a supply compartment 14', a middle compartment 15, and a discharge compartment 16. As shown in Figure 3, the partition 12 is preferably somewhat lower than the partition 13. A suitable supply manifold 20 may betprovided, this manifold being connected with a pulp vat (not shown) through'a supply pipe 21 and a suitable valve 22. A valve may be operated by a convenient hand lever 23. The manifold 20, as shown, may communicate with ment 14 at several different points. Over the inlets may be mounted a suitable splash apron 24. The streams from the several supply in. lets may enter through and serve to agitate the pulp in the supply compartment 14. The pulp from this compartment flows over the baille 12 into the middle compartment 15, any clumps of liber present being broken up by the stream over the top edge of the baille 12. `A portion of the pulp is deposited on the several molds 10, the white p.

the screen on the water passing through molds. The excess pulp suspension flows over the top of the baille 13 and into the discharge compartment 16 whence it escapes through a suitable drain 25 and is pumped back to the vat.

Each mold 10 may rest upon a vertical pipe 30 which projects through the bottom of the flow box. The several pipes 30 communicate with a suction trunk 31 which, in turn, is connected through a suitable valve 32 to a suction pump (not shown). The suction pump should be of sufficient capacity to maintain a relatively high vacuum, of the order of twenty inches of mercury or so. The valve 32 may be conveniently operated by a hand lever'33 extending to the. front of the apparatus.

In order to drain the middle compartment `15, after suflicient pulp has been deposited on the molds 10, extending preferably the entire length of the ilow box.. This gate normally closes an opening in the lower portion of the baffle 13, and may be operated as by a series of rods 41 controlled by racks and pinions 42, or by any other suitable mechanism. The bottom of the flow box may be sloped as at 43 (Figure 2) the supply compartthe bottom of the box I may provide a sluice gate toward the outlet 25 to facilitate the draining of the middle compartment 15 after an operation of the apparatus.

In molding articles, the lever`v23 is operated to open the supply valve 22 and to admit into the flow box a stream of long, unbeaten Wood pulp ber in a dilute aqueous suspension. Fiber of this kind is a practical necessity in forming articles in this manner, since short or slow fibers quickly form a more or `less impermeable mat on the surface of the molds so thatKL the rateof deposit of ber thereon quickly drops to almost nothing. By the use of a high vacuum within the mold and a free long bered stock 0n the outside of the mold, a thick water-laid layer` of ber may be deposited on the molds-'in a very few minutes. By this method a wall thicknessl ofthe order of one half to three quarters of an inch is readily obtained. The thickness is ordinarily not even, the ber forming in such a manner as to present a rough, somewhat ribbed outer surface. This feature is of practical value in the formation of certain articles such as bell-mouth ends for conduits, as

shown in Figure 4. The inner surfaces of these bell mouth ends are formed comparatively smooth, since these surfaces are formed against the wire of the mold itself. The outer surfaces of the bell mouth ends are rough and uneven so that`when the article is embedded in concrete, the concrete shapes itself to the irregularities of the outer surface and Lecurely anchors the bell mouth end.`

In operating the apparatus, thesluice gate 40 is rst closed, then the valve 22 is opened to admit a stream of pulp stock. This stock fills the supply compartment 14, overflows into and lls the middle nally spills over the baie 13 into the discharge compartment 16. As soon as the compartments 32 is opened to apply suction to the interior of the molds 10. An excess of stock is kept circulating through the compartments and out through the drain 25. After a suitable period of time, usually about ve to ten minutes, the valve 22 may be closed, the slulce gate 40 opened, and subsequently the valve 32 may be closed to break the vacuum w1th1n the molds and to permit their removal together with the molded articles formed thereon. The articles themselves maybe thereupon removed from the molds and allowed to dry, after which they may be further treated by saturation with waterproong materials,-

or in any other desired manner.

Vhile the drawings show a set of molds suitable for making bell mouth ends, various other articles may be made in the same manner. In case the same wall thickness is desired for different articles, different shapes i of molds may be used simultaneously.

I claim:

1.A. method of molding articles of pulp,

compartment 15, and

14 and 15 have been lled, the valve which comprises setting' up a, stationary screen mold, flowing an aqueous suspension of long ber unbeaten wood pulp around and over said mold, maintaining a substantial vacuum 2. Apparatus of the class described comprising a flow box, a pair of partition walls in said box dening a supply compartment, a

middle compartment and a discharge compartment therein, the partition between the middle and discharge compartments being higher than the partition between the middle and 'supply compartments, a supply pipe leading into said supply compartment, a discharge pipe leading from said discharge compartment; a screen mold in said middle compartment, and means connecting with the interior of said mold for maintaining a vacuum therein.

3. Apparatus of the class described comprising a flow box, a pair of partitionl walls three compartments, a screen mold mounted 1n the compartment between the two partitions, a supply pipe entering the other compartment adjacent tothe lower partition, a,

discharge pipe leading from the other compartment adjacent 7to the higher partition, said higher partition having a sluice gate in the lower portion thereof, and suction means communicating with the interior of said screen mold.

4. Apparatus of the class described comprising an elongated flow box, a pair of partitions extending from end to end of said box and forming a supply compartment, a middle compartment, and a discharge compartment nature.

BERTWELL C. ROOT.

-of unequal height in said flow box defining l sus 

